Apparatus for winding

Abstract: A method and apparatus for the preparation of a wound roll (6) of a web of material (12) by utilizing a surface windup device with a primary lay-on roll (1) that feeds the web of material (12) onto a rotating core, winding the web (12) onto the core to form a roll (6) by driving the roll of material (6) with a secondary lay-on roll (2), the differential in surface speed between the primary and secondary lay-on rolls (1,2) controls the tension of the web (12) as it is wound. Also incorporates are a retractable cutting roll (5) and knife (4) assembly that is moved into position to cut the web of material (12), assist in transferring the web of material (12) to a new core and then retracts to a position that does not hinder winding the new roll of wound material (6).

Description: FIELD OF THE INVENTION This invention relates generally to an improved apparatus for winding a web of material into a roll wherein the tension and compression of the web of material is controlled as it is wound, and automatically cuts the web of material and starts a new roll and ejects the finished wound roll of material. BACKGROUND OF THE INVENTION Heretofore, in winding or rewinding a web, a dancer roll has been used for the purpose of absorbing tension variation and thereby controlling tension. However, dancer rolls can create creases in thinner films and the edges of the wound films cannot be aligned and a dancer still imparts tension into the web of material being wound. In some winders, a method of adjusting tension by controlling the torque of a motor shaft is generally employed or the tension is detected by means of a fixed roll. A typical means for detecting tension exerted upon a sheet and controlling the same is by the use of a dancer roll. The tension exerted upon the sheet is detected as an electric signal derived from a displaced dancer roll actuating a potentiometer or the like. After comparing this detected signal with a preset value, a driving force is controlled, so as to bring the dancer back to its set position and thereby exerting tension upon the sheet to a predetermined value. This type of apparatus has a disadvantage in that the follow-up characteristic of a dancer roll, i.e., its response to film tension, is not sufficiently high. In addition, by definition, there is always some amount of tension that the dancer must impart into the web to properly monitor and operate the drive control. Thus, a typical dancer arrangement cannot be used to achieve zero tension in the web being wound. Another method employed to control tension is an apparatus in which current through a motor for driving a spool or core is detected (when the tension of a sheet being taken up becomes small, the torque of the motor is reduced and thus the current through the motor is reduced) and thereby the tension exerted upon the sheet is detected. In order to compare the tension of the sheet with a preset value, the detected current signal is led to a current control system in which the current signal is compared with a preset current value for the motor in order to control the motor current. However, this type of apparatus also involves problems in that the response characteristic for tension control is poor because of the inertia of the mechanical system, and the sheet is unevenly stretched owing to variations in tension. Assuming that controls similar to those in the aforementioned winders are employed in a rewinder, since such material as sound film is generally kept intact for several days for aging purposes before it is rewound by a rewinder, air wound jointly with the film escapes resulting in an eccentric deformation of the wound film. As a result, variation in tension is far larger than that which occurs upon winding, and the rewinding becomes impossible. As described above, there are many disadvantages in the prior art methods. More particularly, in a rewinder having a dancer roll, tension of a film cannot be measured precisely because of the mass of the dancer roll, and the r.p.m. of the spool becomes equal to or higher than the resonant frequency of the vibration system consisting of the mass of the dancer roll, the bracket supporting same and the spring or other type of tensioning mechanism used for the dancer roll, not only does the capability of detecting tension diminish, but also the rewinding operation per se becomes impossible because of the vibration of the dancer roll. As stated previously, a wound film is kept intact for several days for the purpose of aging. Furthermore, assuming that controls similar to those in the aforementioned winders are employed in a rewinder, since such material as polyethylene foam or the like, go through an aging process in which the web of material experiences post expansion, and since the web of material wound into a roll is confined to a given space, any expansion of the web of material that does take place is mirrored by an equal amount of compression of the web of material in other parts of the roll. In general, the outer layers of the web in the roll will expand and as they expand, they compress the inner layers of the web within the roll. As a result, variation in thickness in the web of material tends to remain in the web of material even after its is rewound using conventional winding methods. In addition, most thermoplastic film or sheet experiences some stretching during processing and if controls similar to those in the aforementioned winders are employed in a winder or a rewinder, the amount of stretching that occurs tends to remain in the material until it is unwound and left in a free state without any external forces. Over time the material will tend to contract and relax in the direction of the stretch and assume a new dimensional geometry. If a product is die cut, for instance, before the product has reached a relaxed state, then dimensions of the cut product will change once the product relaxes and its dimensions may exceed the acceptable tolerances and it may have to be discarded as scrap. Other post processing operations such as skiving or thermoforming often requires a material that has low stress in it. However, using controls similar to those in the aforementioned winders or rewinders, some stress and orientation can be imparted into the material. Winders are an important apparatus in many manufacturing processes, such as, making cable, film, sheet or other strand or web type materials which have many beneficial industrial and commercial uses particularly in the packaging industry. The method and apparatus employed by winders are described in the U.S. Patents listed below as well as in other literature pertaining to the design and method of operation. In US-A-3,057,572 there is disclosed a winding machine having a rotatable rewind roll adapted to have web material wound thereon. The rewind roll rests upon a pair of rotatable winding drums. The drums are in frictional engagement with web material on the rewind roll at spaced circumferential points of the latter. The rewind roll is capable of ascending as web material accumulates thereon. Driving means are provided for driving the drums at slightly different surface speeds. The driving means comprise a driving motor connected in driving relation to one of the drums, a compound, epicyclic differential gear mechanism having a rotary input element connected in driving relation to said motor, a rotary output element connected in driving relation to the other of said drums, and a reducing train comprising plural sets of epicyclic gears in driving relation between said input and output elements and a rotary control gear meshing with a gear in said differential gear mechanism. An auxiliary motor is connected in driving relation to the control gear and substantially non-stallable at torques imposed upon said control gear. Synchronizing means are connected between the motors for maintaining the relative speeds of the motors at a predetermined ratio. U.S. Patent No. 3,429,517 discloses a double layer winding device, especially for textiles webs, which operates in conformity with the duplex winding with two hank rollers of changing direction of rotation for storing the goods which are withdrawn in a continuous uninterrupted. U.S. Patent No. 3,503,526 describes an apparatus for winding or unwinding continuous webs of non-conductive material, the apparatus incorporating an alpha particle-emitting device directed toward a winding or unwinding roll or web beyond the point of tangency between the web and roll. U.S. Patent No. 3,506,211 discloses an apparatus for cutting and coiling webs of paper, corrugated cardboard and the like comprising a coiling bar in the form of a shaft which is activated at one end and mounted at the other end in a removable bearing which makes use of a mechanical movable arrangement along the winding bar. U.S. Patent No. 3,514,046 describes an apparatus including a pair of windup reels selectively positionable to be driven for winding up a strip of material received from an adjacent processing apparatus. U.S. Patent No. 3,514,047 describes an apparatus including a utilized surface windup device for automatically introducing a core within the nest of the winding drums, cinching the end of a web around the core, winding the web onto the core to form a roll, and ejecting the wound roll from the nest. A method for automatically attaching the trailing end of the web to the outer convolution of a wound roll and a method for automatically cleaning the winding drum. U.S. Patent No. 3,602,448 describes an apparatus winding a web on a rotating reel, an ironer assembly for smoothing the web as it is added to the reel, including an ironer roll which rides on the reel , a pivotally suspended frame larger in mass than the ironer roll, and springs under compression between the frame and roll for resiliently supporting the frame on the roll, so that the weight of the frame augments the pressure exerted by the roll on the web. U.S. Patent No. 3,630,462 describes a web winding an apparatus including a reel on which a roll being wound is contacted by a rider roll, and a potentiometer associated with the rider roll monitors the roll buildup and controls a DC-indexing motor to rotate the winding-roll away from the rider roll to maintain substantially constant circuit controls the acceleration and deceleration of the indexing motor as the rolls are being changed to permit web tension to be maintained constant. U.S. Patent No. 3,677,484 describes a thin layer material having a large width can be wound up around a winding core by continuously supplying and inserting an elongated continuously supplying and inserting an elongated continuous yarn-like material, which transverses the thin layer material, in between one wound layer and another to leave a clearance along the inserted yarn-like material. U.S. Patent No. 3,749,328 describes an air-permeable member is secured to the end of a tube carried by a pivotally-mounted guide arm, said member being positioned between the flanges of a tape reel and mechanically biased toward the reel hub as a strip of tape is wound onto the hub. U.S. Patent No. 3,794,268 describes a method and apparatus for winding a hollow, flexible tubular material in a manner which permits the tubular material to be removed from its support and simultaneously filled continuously for packaging or other purposes. U.S. Patent No. 4,050,642 describes a method and apparatus for winding a film wherein a pressurized jet of air is directed onto a surface of an unsupported portion of the film being wound or rewound. The above mentioned patents do not disclose the method and apparatus for reducing the tension of the sheet or web as it is wound or reducing roll compression exerted by a lay-on roll when surface winding through the use of a secondary lay-on roll with a differential speed adjustment relative to the primary lay-on roll speed or the use of a torque motor to control the pressure exerted between the roll being wound and the lay-on roll that turns the roll being wound. When less tension or compression was desired in a material wound on a roll, it has previously been necessary to loosen the material on the wound roll after winding or rewind the roll in a secondary operation off-line. This additional procedure adds labor, and therefor costs, to the product, and moreover, results in added handling and exposure of the material to the potential of marking, soiling, crimping, and or types of damage that result in poor aesthetic and/or functional qualities, reducing the value of the material and/or its structure. Furthermore, these patents do not disclose the use of a roll surface made up of a material that is softer than the web of material being wound and thus the roll with a soft covering behalves more like a flat surface which reduces point to point contact that most surface winders exhibit. In addition, a tucking device or tucking roll is not disclosed in the above patents nor is a retractable cutting roll and knife assembly to cut the web of material. US-A-1 680 979 discloses an apparatus for winding comprising the features of the preamble of claim 1. SUMMARY OF THE INVENTION This invention has been proposed with a view to obviating the aforementioned disadvantages in the prior art, and it is an aim of the present invention to provide a novel method of winding or rewinding process which eliminates many of the problems encountered with the current winding technologies and techniques even if a web of material is wound at very high speed. This patent provides a technique for reducing the tension of the sheet or web as it is wound and reduces roll compression exerted by a lay-on roll when surface winding. With less tension and compression being imparted into the web of material wound on a roll when the method and apparatus described in this patent is used, the need of loosening the web of material on the wound roll after winding is reduced or eliminated as well as the need to rewind the roll in a secondary operation off-line. The elimination of these additional procedures reduces labor, and thereof costs, to the product, and moreover, results in less handling and exposure of the web of material to the potential of marking, soiling, crimping, and or types of damage that result in poor aesthetic and/or functional qualities, improving the value of the web of material and/or its structure. The present invention is accordingly directed to the combination of features set out in claim 1 of the present specification. Advantageous developments of the present invention are set out in sub-claims 2 to 21. In one embodiment of the present invention, the aforementioned aim can be achieved during the winding or rewinding process by the use of a secondary lay-on to drive the rotation of the winding roll, in conjunction with a primary lay-on roll that is in close proximity to the winding roll, but not touching it and whose function, in general, is to present the web onto the winding roll at a speed equal to or greater than the surface speed of the outside surface of the winding roll. The winding roll's rotation or speed is controlled by the secondary roll. When the winding roll's rolls surface speed moves slower than the speed of the web of material it is winding, then the web will be wound with decreased tension. BRIEF DESCRIPTION OF THE DRAWING Figure 1 and 2 are schematic representations of the disclosed winder. Figure 1 is a schematic cross-section of an apparatus for practicing the method of the invention when in the normal running position. Figure 2 is a schematic cross-section of an apparatus for practicing the method of the invention when in the normal cutting position to transfer the web of material being wound into a roll onto a new core to begin a new roll. DETAILED DESCRIPTION OF THE INVENTION In Figure 1 the web of material 12 being wound, is wrapped around the primary lay-on roll 1 . Preferably the web of material 12 being wound has at least a 90 ° wrap around the primary layon roll 1 , although less of a wrap can be used. The wrap refers to the angular distance in which the web of material 12 is against a roll's surface. The primary lay-on roll 1 presents the web of material 12 to the roll of material 6 being wound. The primary lay-on roll 1 is rotated by is own motor and its speed is controlled by potentiometer or similar device. In some arrangements the speed of the primary lay-on roll 1 is controlled or regulated by a dancer roll 11 whose movement varies with the tension of web of material being wound 12 . The pressure the dancer roll 11 exerts against the web of material 12 can be varied to increase or decrease the tension of the web of material 12 being wound. After the web of material 12 is placed onto the roll of material 6 being wound, it moves in unison with the roll of material 6 being wound. After the web of material 12 is placed on roll of material 6 being wound it encounters the secondary lay-on roll 2 . The rotation of the secondary lay-on roll 2 causes the roll of material 6 being wound to rotate at the same approximate surface speed as the surface speed of the secondary lay-on roll 2 . The secondary lay-on roll 2 has its own drive motor. The speed of the secondary lay-on roll 2 is regulated as a function of the ratio, which is adjustable, to the speed of the primary lay-on roll 1 . Therefore, as the speed of the primary lay-on roll 1 increases or decreases, the secondary lay-on roll 2 increases or decreases the same amount so that primary lay-on roll 1 and the secondary lay-on roll 2 maintain the same relative speed ratio. In addition, since the secondary lay-on roll 2 can be run at a speed that is slower or faster speed relative to the speed of the primary lay-on roll 1 , the speed of the roll of material 6 being wound, can be adjusted by changing the speed of the secondary lay-on roll 2 to increase or decrease tension in the web of material 12 as it is placed onto the roll of material 6 being wound, thus providing a method to control and manipulate tension of the web of material 12 in the roll heretofore unknown. A further benefit can be achieved by covering the secondary lay-on roll 2 with soft material that can compress when pushed against the roll of material 6 being wound. If the secondary lay-on roll 2 covering compresses, the surface it presents to the roll of material 6 being wound appears flatter. A flatter appearing secondary lay-on roll 2 reduces the compression of the web of material 12 on the roll of material 6 being wound that would normally occur in point to point contact of two rolls especially if the secondary lay-on roll 2 had a firmer material on it. The roll of material 6 being wound is mounted on a shaft 14 whose ends rest in holders 10. The holders 10 support the shaft 14 at both ends and allows the roll of material 6 being wound to rotate as the web of material 12 is wound on it. As web of material 12 is wound on the roll of material 6, the diameter of the roll of material 6 being wound increases which pushes the holders 10 further from secondary lay-on roll 2 while the roll of material 6 remains in contact with and continues to be turned by the secondary lay-on roll 2. The holders 10 are connected to one another by a chain and jack-shaft assembly. The movement of the assembly is controlled by a torque motor 8. The torque motor 8 can move the holders in or out, or it can control the pressure exerted by the roll of material 6 being wound against the secondary lay-on roll 2. Figure 2, shows the roll change position. Once the desired length of web of material 12 is wound on roll of material 6 being wound, a retractable cutting roll 5 and cutting knife 4 are moved into position to cut the web of material 12 and transfer it to a start-up roll 15 so that a new roll of material 6 can be wound. After the transfer of the web of material 12 is made to the start-up roll of material 15 and a new roll of material 6 is winding, the cutting roll 5 and cutting knife 4 are retracted and moved to the run position where they will not hinder the winding of the new start-up roll 15. The cutting knife 4 may comprise a plurality of blades aligned in a row and directed towards the path of the web of material 12 being wound. Transfer means may be provided for transferring the web of material 12 to a second winding roll after the web is cut so that a second roll of the material can be wound.

Claims: Apparatus for winding, comprising: a winding roll (6) for accumulating a web of material (12); distribution means (1) for distributing the said web of material (12) onto the said winding roll (6); drive means (2) for effecting rotation of the said winding roll (6) and for effecting rotation of the said distribution means (1); and a regulator for maintaining a constant surface speed ratio between the said winding roll (6) and the said distribution means (1), characterised in that the distribution means (1) is adjacent to but spaced from the web material (12) which has accumulated on the said winding roll (6). Apparatus according to claim 1, characterised in that the distribution means (1) is a lay-on roll (1). Apparatus according to claim 1 or claim 2, characterised in that the surface speed ratio between the said winding roll (6) and the said distribution means (1) is adjustable. Apparatus according to any preceding claim, characterised in that the said drive means (2) and the said distribution means (1) have separate drives, and wherein the said drives are synchronized so that their surface speeds are maintained at a constant ratio. Apparatus according to any preceding claim, characterised in that the said distribution means (1) is in direct contact with the said web of material (12) being distributed onto the said winding roll (6). Apparatus according to any preceding claim, characterised in that the said web of material (12) being distributed onto the said winding roll (6) contacts the said distribution means (1) at at least a 90° wrap. Apparatus according to any preceding claim, characterised in that the said regulator is a motor which forms part of the said drive means and which is responsive to changes of the surface speed of the said distribution means (1). Apparatus according to any preceding claim, characterised in that the tension of the said web of material (12) being wound is controlled by a dancer roll (11). Apparatus according to claim 1, characterised in that the tension in the said web of material (12) is adjustable by changing the said surface speed ratio. Apparatus according to any preceding claim, characterised in that the apparatus further comprises: severing means (4 and 5) for severing the said web of material (12) when the said winding roll (6) is sufficiently full. Apparatus according to claim 10, characterised in that the said severing means (4 and 5) is a retractable cutting roll (5) and knife (4) assembly. Apparatus according to claim 11, characterised in that the said retractable cutting roll (5) is driven by the said distribution means (1). Apparatus according to claim 11 or claim 12, characterised in that the said retractable cutting roll (5) is driven by the said distribution means (1) in conjunction with a variable speed reducer. Apparatus according to any one of claims 11 to 13, characterised in that the said retractable cutting roll (5) is driven by its own motor and is synchronized with the angular velocity or surface speed of the said distribution means (1). Apparatus according to claim 10, characterised in that the said knife (4) assembly comprises a plurality of blades aligned in a row and directed towards the path of the said web of the material (12) being wound. Apparatus according to claim 9, characterised in that the apparatus further comprises: transfer means for transferring the said web of material (12) to a second winding roll after the said web is cut so that a second roll of the said material can be wound. Apparatus according to claim 16, characterised in that the said transfer means is a roll. Apparatus according to claim 16, characterised in that the said transfer means is a tucking device. Apparatus according to claim 8 or any one of claims 9 to 18 read as appended to claim 8, characterised in that the dancer roll (11) is capable of exerting adjustable pressure against the said web of material (12) before the said web of material (12) passes to the said distribution means (1). Apparatus according to claim 19, characterised in that the pressure exerted by the dancer roll (11) varies as a function of the tension in the web of material (12). Apparatus according to claim 19 or claim 20, characterised in that the speed of the outer surface of the distribution means (1) is controlled by the dancer roll (11).

Inventors: KNAUS DENNIS A, KNAUS, DENNIS A.
Applicants: KNAUS DENNIS A, KNAUS, DENNIS A.
Application year: 1994
Main classification: B65H18
IPC codes: B65H23, B65H19, B65H18